The New York Times reports that the video was secretly recorded by a teacher’s assistant who has since quit her job there. She was not identified because she fears retribution in her future employment. The teacher’s assistant recorded the video in the fall of 2014.

A spokeswoman for Success Academy, Ann Powell, described the video as shocking, and said Dial had been suspended. But she returned to the classroom a week later.

According to The New York Times own investigation, the teacher’s actions are not an anomaly. Interviews with 20 former and current educators there say Dial’s tactics are not uncommon.

“It’s this culture of, ‘If you’ve made them cry, you’ve succeeded in getting your point across,’” said a former teacher, Jessica Reid Sliwerski.

A Twitter account that identifies itself as Success Academy responded Friday to the controversy.